Android 软键盘不能弹出

记录一次软键盘不能调出来的问题

一、前提条件

设置其所在Activity，AndroidManifest.xml属性 android:windowSoftInputMode=“stateVisible|adjustResize”
EditText点击本身的话，据系统规则会调用起软键盘

二、操作表现

点击EditText，系统没有调用软键盘，不知为何原因？
故手动调用软键盘看能不能调用起来

InputMethodManager imm = (InputMethodManager) getSystemService(INPUT_METHOD_SERVICE);
imm.showSoftInput(mContentEditText, InputMethodManager.SHOW_FORCED);

发现仍然不能调用起软键盘，故Debug showSoftInput的源代码

三、追踪问题

1、只有Debug showSoftInput源代码，最终定位到

public boolean showSoftInput(View view, int flags, ResultReceiver resultReceiver) {
        checkFocus();
        synchronized (mH) {
            if (mServedView != view && (mServedView == null
                    || !mServedView.checkInputConnectionProxy(view))) {
                return false;
            }

            try {
                return mService.showSoftInput(mClient, flags, resultReceiver);
            } catch (RemoteException e) {
                throw e.rethrowFromSystemServer();
            }
        }
    }

发现传过来的view是EditView，没有任何问题，问题在mServedView != view返回为true，mServedView竟然为另外的view，故不能向下调用mService.showSoftInput(mClient, flags, resultReceiver)去启用软键盘

2、寻找mServedView的赋值位置，

private boolean checkFocusNoStartInput(boolean forceNewFocus) {
        // This is called a lot, so short-circuit before locking.
        if (mServedView == mNextServedView && !forceNewFocus) {
            return false;
        }

        final ControlledInputConnectionWrapper ic;
        synchronized (mH) {
            if (mServedView == mNextServedView && !forceNewFocus) {
                return false;
            }
            if (DEBUG) Log.v(TAG, "checkFocus: view=" + mServedView
                    + " next=" + mNextServedView
                    + " forceNewFocus=" + forceNewFocus
                    + " package="
                    + (mServedView != null ? mServedView.getContext().getPackageName() : ""));

            if (mNextServedView == null) {
                finishInputLocked();
                // In this case, we used to have a focused view on the window,
                // but no longer do.  We should make sure the input method is
                // no longer shown, since it serves no purpose.
                closeCurrentInput();
                return false;
            }

            ic = mServedInputConnectionWrapper;

            mServedView = mNextServedView;
            mCurrentTextBoxAttribute = null;
            mCompletions = null;
            mServedConnecting = true;
        }

        if (ic != null) {
            ic.finishComposingText();
        }

        return true;
    }

最终定位于Activity中EditView的焦点失去，导致mServedView重新被赋值，mServedView = mNextServedView;
所以… …